I like to play Fortnite on my MacBook Pro but my computer stays consistently hot

Apple laptops normally run hot when being used and is perfectly normal especially when playing a game. While heat does cause wear on the computer, computers are meant to be used. The CPU will be throttled if the system fans cannot keep the CPU running under the maximum safe temperature. For extreme cases the computer will power down in the event the temperatures go over the manufacturer's maximum temperature which is especially rare these days due to the throttling of the CPU to control temperatures. Enjoy playing Fortnite.

I advise that while using the MBP under such a load you keep it on a hard surface to let all of the heat-reduction surfaces and ports be exposed to open air. Aside from that, enjoy the game!